1. Field of the Invention
The present invention relates to an inkjet head adapted for use in an inkjet printer, which ejects ink droplets and records by printing various images on a target-recording medium.
2. Description of the Related Art
Hitherto, an inkjet recording device is well known, which records by printing characters and images on a target recording medium by using an inkjet head having a plurality of nozzles, which eject ink. FIGS. 11, 12, and 13 are a perspective view, a schematic elevational view, and a schematic cross-sectional view, respectively, illustrating an example of such an inkjet head, and FIG. 14 is an exploded view illustrating an actuator section which generates pressure necessary for ink-ejection and a peripheral portion of the nozzles from which ink is finally ejected.
As shown in FIG. 14, a piezoelectric ceramic plate 1 has a plurality of channels 5 which are juxtaposed in parallel, and respective channels 5 are separated from one another by sidewalls 21.
One end section of each channel 5 is longitudinally extended to one edge face of the piezoelectric ceramic plate 1 while the other end section of the channel 5 does not extend to the other edge face of the plate, so that the channel depth becomes gradually shallower toward the other end section.
Moreover, electrodes 4 for applying a driving electric field are formed on the open-side faces of both sidewalls 21 for each channel 5 so as to extend along the longitudinal direction.
Furthermore, an ink chamber plate 2 constituting a common ink chamber 6, which communicating with the shallower end section of each channel 5 is connected to the piezoelectric ceramic plate 1 on the open sides of the channels 5 so as to form a head tip 26. A nozzle plate 3 is connected to the end face of a composite body consisting of the piezoelectric ceramic plate 1 and the ink chamber plate 2, where the channels 5 open up from the composite body and nozzle holes 11 are formed at positions of the nozzle plate 3 facing respective channels 5. The nozzle plate 3 and the head tip 26 are fixed by a head cap 12, and the electrodes 4 formed on the head tip 26 and a driving circuit board 14 are connected by a flexible board 19.
Moreover, an ink flow-channel member 40 to supply ink to the common ink chamber 6 is fixed to the ink chamber plate 2, an ink inlet port 41 for introducing ink is formed at the center of the flow-channel member 40, and a pressure relief unit 70 for absorbing any fluctuation in pressure during the printing operation is connected to the ink inlet port 41. Furthermore, since a filter 7 is fixed to the flow-channel member 40 so as to prevent foreign materials from flowing into and plugging the nozzle holes 11 and since the filter 7 partitions the flow-channel of the flow-channel member 40, the flow channel of the flow-channel member 40 is separated into an ink reservoir A 10 located on the upstream side of the nozzle holes 11 and an ink reservoir B 43 located on the downstream side of the nozzle holes 11. These parts and elements are eventually fixedly mounted on the base 13 made of an aluminum material.
In an inkjet head configured in this manner, when ink is filled in each of the channels 5 through the pressure release unit 70 and the flow-channel member 40 and when a predetermined driving electric field is applied to a predetermined channel 5 through the electrodes 4, the volume in a predetermined channel 5 changes due to the deformation of the sidewalls 21, resulting in ink in the predetermined channel 5 being ejected from the corresponding nozzle hole 11.